OTTAWA – With the growing availability of fentanyl test strips on store shelves and online, Health Canada would like to remind Canadians of the potential limitations when using fentanyl test strips to detect fentanyl or other deadly substances in street drugs before consuming them.

No fentanyl test strips are specifically designed to check street drugs before consumption. Some strips are designed to detect fentanyl and some analogs (similar chemicals, such as carfentanil) in an individual's urine sample to determine whether they have taken the drug. Others are designed to detect fentanyl and some analogs in substances that are, for example, seized by law enforcement. Therefore, it is important that people who are using fentanyl test strips to check street drugs before consuming them understand the limitations and use the necessary precautions.

Health Canada is reminding Canadians that to help prevent a fatal overdose, it is important to treat all street drugs as though they are potentially contaminated with unknown deadly substances.

Use every precaution, even if you or your friends use fentanyl test strips:

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Limitations of fentanyl test strips

In December 2017, Health Canada advised Canadians about the potential limitations of fentanyl test strips when used to check street drugs before consumption. A preliminary study by the Department of a fentanyl test strip product indicated that false negatives could occur. A false negative result means that the test strip did not detect a targeted drug even though the drug was present in the sample. A false negative could lead to a false sense of security, which may result in drug use that could lead to overdose or death.

Health Canada has undertaken additional assessments of the same fentanyl test strip and found that while the product detected fentanyl every time, it was not reliable for detecting some fentanyl analogs. This includes carfentanil, a drug that is far more toxic than fentanyl.

Test strips may not always detect a drug, even ones they are designed to target. There are many reasons for this:

The test strips may detect only certain substances, such as fentanyl, but not be able to detect other toxic substances that might be present, like carfentanil.

Illegal drugs can be mixed unevenly with other substances so the portion tested may not contain the same amount of the drug that is consumed.

Other substances mixed in the sample could interfere with the accuracy of the test.

The quantity of the sample tested may be too limited to detect a specific substance.

Health Canada is working with companies to include warnings on the packages of test strips that detect the presence of fentanyl and/or its analogs, to better inform consumers about the risks of unreliable results when using the fentanyl test strips to check street drugs they plan to consume.